Gas turbine driven supercharger



March 1, 193's. B; H F A N 2,109,997

GAS TURBINE DRIVEN SUPERCHARGER Filed Jan. 11, 1957 Fig. 2.

' /2 7 Pi .I. l2 l5 g /9 f /9 20 III I m 1/ 9 kg: 24 26 v 23 I4 I I /////k I Ivwventow: Bruno Hoffmahn,

H is Att orvw ey.

Patented Mar. 1, 1938 UNITED STATES GAS TURBINE DRIVEN SUPERCHARGER Bruno Hoffmann,

Berlin-Spandau-West, Germany, assignor to General Electric Company, a corporation of New York Application January 11, 1937, Serial No. 120,135 In Germany January 20, 1936 3 Claims.

The present invention relates to gas turbine driven superchargers such as are used in aircraft for supercharging internal combustion engines. The gas turbine or turbines for driving the superchargers in such arrangements receive their operating medium in the form of gases discharged or exhausted from an internal combustion engine. These gases have high'temperature and cause considerable heating of the gas turbine wheel. Precaution has to be taken therefore to avoid excessive heating of the turbine shaft and the transmission of such heat to other parts of the plant.

The object of my invention is to provide an improved construction and arrangement whereby the bucket wheel of the gas turbine is effectively cooled and the transmission of heat from the bucket wheel to other parts associated therewith is considerably reduced.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto in connection with the accompanying drawing.

In the drawing, Fig. 1 is a sectional view along lines l-l of Fig. 2 of an exhaust gas turbine driven blower or supercharger embodying my invention, and Fig. 2 is a front view of Fig. l.

The arrangement comprises a blower ID with 30 an impeller II and a discharge scroll l2. The

scroll has a plurality of openings I3 for connection to the various cylinders of a combustion engine. The impeller is secured, in the present instance integrally formed, with a hollow shaft I4.

35 The shaft is supported on an overhung shaft portion I! which may form a part of the crank shaft of the engine to be supercharged. The support is accomplished in the present instance by means of a friction bearing l6 for the left-hand end of 40 the hollow shaft l4 and a ball-bearing H for an intermediate portion of the shaft l4. The righthand end portion of the shaft I4 is overhung with regard to the bearing IT. The supercharger, that is the shaft I, with the impeller H is driven by 46 a gas turbine which comprises a bucket wheel I8 secured to the overhung portion of the shaft H. A nozzle box I9 having a plurality of nozzles 20 and an inlet opening 21 is associated with the bucket wheel and disposed intermediate the wheel 0 and the supercharger. To reduce the transfer of heat from the disk of the bucket wheel l8 the latter is heat-insulated from the overhung portion of the shaft II by a member 22 made of a material of poor heat-conductivity.

56 In accordance with my invention the bucket wheel I8 is cooled and thereby the transmission of heat therefrom to the shaft l4 and other parts associated therewith is considerably reduced by the provision of an auxiliary blower or fan having a plurality of vanes or blades 23, in the present instance integrally united with the shaft i4 and disposed intermediate the bucket wheel and the supercharger casing and inside the annular space defined by the nozzle box IQ of the gas turbine. The auxiliary fan or blower 23 also includes a casing 24 for properly conducting air from the atmosphere to the inlet side of the blades 23 and discharging it therefrom toward the bucket wheel I8. To improve the cooling effect on the wheel and to facilitate the discharge of the air, the 'hub of the bucket wheel is provided with a plurality of annular projections 25 on both sides of the bucket wheel disks and these annular projections on the bucket wheel l8 are provided with a plurality of circumferentially spaced openings 26 which also extend through the bucket wheel disk. -The outer side of the bucket wheel I8 is completely exposed to the atmosphere.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Exhaust gas turbine driven supercharger for aircraft including the combination of a supercharger, an axial flow gas turbine having a bucket wheel secured to the shaft of the supercharger with one side of the bucket wheel directly exposed to atmosphere, means for conducting gas to the bucket wheel comprising a nozzle box arranged intermediate the wheel and the supercharger, and auxiliary blower means for cooling the side of the bucket wheel adjacent the supercharger.

2. Exhaust gas turbine driven supercharger for aircraft including the combination of a supercharger having a shaft and an impeller integrally formed on the shaft, a gas turbine having a bucket wheel secured to said shaft, an annular nozzle box for supplying gases to the bucket wheel being disposed intermediate the wheel and the supercharger, and means for cooling the bucket wheel including an auxiliary blower having an impeller secured to the shaft intermediate the bucket wheel and the impeller and within an annular space defined by the nozzle box.

3. Exhaust gas turbine driven supercharger for aircraft including the combination of a supercharger having a shaft and an impeller secured thereto, a gas turbine having a bucket wheel secured to an overhung portion of said shaft and a nozzle box disposed intermediate the bucket wheel and the impeller, means for cooling the bucket wheel and reducing transmission of heat openings through said projections, and an auxiliary blower having an element secured to the shaft intermediate the impeller and the bucket wheel for forcing cooling air from the atmosphere towards the bucket wheel.

BRUNO HOFFMANN. 

